<p>We study the connections between operator moment sequences <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2024_1649_Article_IEq3.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="98" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\mathcal {T}}}=\displaystyle (T_n)_{n\in {\mathbb {Z}}_+}\)</EquationSource> <EquationSource Format="MATHML"><math> <mstyle displaystyle="true" scriptlevel="0"> <mrow> <mi mathvariant="script">T</mi> <mo>=</mo> <msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>T</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>∈</mo> <msub> <mi mathvariant="double-struck">Z</mi> <mo>+</mo> </msub> </mrow> </msub> </mrow> </mstyle> </math></EquationSource> </InlineEquation> of self-adjoint operators on a complex Hilbert space <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2024_1649_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {H}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">H</mi> </math></EquationSource> </InlineEquation> and the local moment sequences <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2024_1649_Article_IEq5.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="179" /> </InlineMediaObject> <EquationSource Format="TEX">\(\langle {{\mathcal {T}}}x,x\rangle = (\langle T_nx,x\rangle )_{n\in {\mathbb {Z}}_+}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mrow> <mo stretchy="false">⟨</mo> <mi mathvariant="script">T</mi> <mi>x</mi> <mo>,</mo> <mi>x</mi> <mo stretchy="false">⟩</mo> </mrow> <mo>=</mo> <msub> <mrow> <mo stretchy="false">(</mo> <mrow> <mo stretchy="false">⟨</mo> <msub> <mi>T</mi> <mi>n</mi> </msub> <mi>x</mi> <mo>,</mo> <mi>x</mi> <mo stretchy="false">⟩</mo> </mrow> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>∈</mo> <msub> <mi mathvariant="double-struck">Z</mi> <mo>+</mo> </msub> </mrow> </msub> </mrow> </math></EquationSource> </InlineEquation> for arbitrary <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2024_1649_Article_IEq6.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="50" /> </InlineMediaObject> <EquationSource Format="TEX">\(x\in {\mathcal {H}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>∈</mo> <mi mathvariant="script">H</mi> </mrow> </math></EquationSource> </InlineEquation>. We provide necessary and sufficient conditions for solving the operator moment problem on <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2024_1649_Article_IEq7.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathbb {R}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">R</mi> </math></EquationSource> </InlineEquation>, and we show that these criteria are automatically valid on compact subsets of <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2024_1649_Article_IEq8.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathbb {R}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">R</mi> </math></EquationSource> </InlineEquation>. Applications of the compact case are used to study subnormal operator weighted shifts. A Stampfli-type propagation theorem for subnormal operator weighted shifts is also established. In addition, we discuss the validity of Tchakaloff’s Theorem for operator moment sequences with compact support. In the case of a recursively generated sequence of self-adjoint operators, necessary and sufficient conditions for an affirmative answer to the operator recursive moment problem are provided, and the support of the associated representing operator-valued measure is described.</p>

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The Local Operator Moment Problem on \({\mathbb {R}}\)

  • R. E. Curto,
  • A. Ech-charyfy,
  • H. El Azhar,
  • E. H. Zerouali

摘要

We study the connections between operator moment sequences \({{\mathcal {T}}}=\displaystyle (T_n)_{n\in {\mathbb {Z}}_+}\) T = ( T n ) n Z + of self-adjoint operators on a complex Hilbert space \({\mathcal {H}}\) H and the local moment sequences \(\langle {{\mathcal {T}}}x,x\rangle = (\langle T_nx,x\rangle )_{n\in {\mathbb {Z}}_+}\) T x , x = ( T n x , x ) n Z + for arbitrary \(x\in {\mathcal {H}}\) x H . We provide necessary and sufficient conditions for solving the operator moment problem on \({\mathbb {R}}\) R , and we show that these criteria are automatically valid on compact subsets of \({\mathbb {R}}\) R . Applications of the compact case are used to study subnormal operator weighted shifts. A Stampfli-type propagation theorem for subnormal operator weighted shifts is also established. In addition, we discuss the validity of Tchakaloff’s Theorem for operator moment sequences with compact support. In the case of a recursively generated sequence of self-adjoint operators, necessary and sufficient conditions for an affirmative answer to the operator recursive moment problem are provided, and the support of the associated representing operator-valued measure is described.